ORIGINAL RESEARCH ARTICLE published: 27 March 2009 NEUROINFORMATICS doi: 10.3389/neuro.11.009.2009 DataViewer3D: an open-source, cross-platform multi-modal neuroimaging data visualization tool André Gouws*, Will Woods, Rebecca Millman, Antony Morland and Gary Green Department of Psychology, York NeuroImaging Centre, University of York, UK Edited by: Integration and display of results from multiple neuroimaging modalities [e.g. magnetic resonance Rolf Kötter, Radboud University imaging (MRI), magnetoencephalography, EEG] relies on display of a diverse range of data Nijmegen, The Netherlands within a common, defi ned coordinate frame. DataViewer3D (DV3D) is a multi-modal imaging Reviewed by: Stephen C. Strother, Baycrest, Canada; data visualization tool offering a cross-platform, open-source solution to simultaneous data University of Toronto, Canada overlay visualization requirements of imaging studies. While DV3D is primarily a visualization David Kennedy, Harvard Medical tool, the package allows an analysis approach where results from one imaging modality can School, USA guide comparative analysis of another modality in a single coordinate space. DV3D is built on *Correspondence: Python, a dynamic object-oriented programming language with support for integration of modular André Gouws, York NeuroImaging Centre, University of York, York Science toolkits, and development of cross-platform software for neuroimaging. DV3D harnesses the Park, York YO10 5DG, UK. power of the Visualization Toolkit (VTK) for two-dimensional (2D) and 3D rendering, calling e-mail: [email protected] VTK’s low level C++ functions from Python. Users interact with data via an intuitive interface that uses Python to bind wxWidgets, which in turn calls the user’s operating system dialogs and graphical user interface tools. DV3D currently supports NIfTI-1, ANALYZE™ and DICOM formats for MRI data display (including statistical data overlay). Formats for other data types are supported. The modularity of DV3D and ease of use of Python allows rapid integration of additional format support and user development. DV3D has been tested on Mac OSX, RedHat Linux and Microsoft Windows XP. DV3D is offered for free download with an extensive set of tutorial resources and example data. Keywords: visualization software, multi-modal neuroimaging, Python, VTK, fMRI, MEG, DTI, DV3D INTRODUCTION and BrainVoyager4. Widely used open-source analysis toolboxes This paper describes DataViewer3D (DV3D), a software package for MATLAB5 are exemplifi ed by Statistical Parametric Mapping built with Python1 and designed and optimized to address many of (Frackowiak et al., 1997), Fieldtrip6, EEGLAB (Delorme and Makeig, the issues encountered when visualizing multi-modal neuroimag- 2004), mrVista (Teo et al., 1997; Wandell et al., 2000) and NUTMEG7. ing data. Stand-alone, cross-platform analysis packages include FSL8 and The combination of analyses from multiple imaging modalities is FreeSurfer9. In addition to analysis packages, a number of stand- an important and growing trend in neuroimaging (e.g. McDonald, alone visualization packages have been developed, some to comple- 2008; Stuffl ebeam and Rosen, 2007). Researchers are conscious of ment particular analysis packages (e.g. FSL’s FSLView10) and others the limitations of individual imaging techniques and their associated independently of analysis packages (MRICron11; 3D Slicer12). analysis methods (e.g. Coltheart, 2006). With sites having access Both analysis and stand-alone visualization packages are often to more than one data acquisition technology, the neuroimaging customized solutions developed by a site to address their specifi c community has the opportunity to compare and contrast results requirements. Many software packages are later extended to pro- from different modalities and analysis approaches. Multi-modal vide analysis frameworks for a more diverse range of hardware techniques are used to exploit differences in results obtained from platforms, data types and analysis methods. Sharing and distribu- different techniques (e.g. Liu et al., 2006) and potentially provide tion of platform independent software with unifi ed data formats converging evidence concerning researchers’ hypotheses. allows the neuroimaging community increased access to analysis A variety of neuroimaging analysis packages are available to researchers, facilitating analysis of data from a complex and 4http://www.brainvoyager.com/ diverse range of data acquisition techniques. The Neuroimaging 5http://www.mathworks.com/products/matlab/ 2 Informatics Tools and Resources Clearinghouse list many of these 6http://www.ru.nl/fcdonders/fi eldtrip/ 3 tools. Commercial analysis software packages include ANALYZE™ 7http://nutmeg.berkeley.edu/ 8http://www.fmrib.ox.ac.uk/fsl/ 9http://surfer.nmr.mgh.harvard.edu/ 1http://www.python.org/ 10http://www.fmrib.ox.ac.uk/fslview 2http://www.nitrc.org/ 11http://www.sph.sc.edu/comd/rorden/mricron/ 3http://www.analyzedirect.com/Analyze/ 12http://slicer.org/ Frontiers in Neuroinformatics www.frontiersin.org March 2009 | Volume 3 | Article 9 | 1 Gouws et al. DV3D in multi-modal neuroimaging methods. Researchers may have to compare the visual outputs of number of core functions when either exploring their data visually two or more different packages side by side, often comparing two- or reporting results to their peers. The key requirements that we dimensional (2D) outputs from one to 3D outputs of another. The have tried to address in the development of DV3D are discussed lack of a like-for-like comparison of results in a uniform coordinate below. They are: space can increase the potential for misinterpretation of results. • Dealing with different data types Reproducibility of results and consistency in analysis, interpreta- • A common space for data tion, and display of results may be compromised when compar- • Co-registration with atlases ing results from different analyses and visualization software (e.g. • Export routines for sharing and publication Mackenzie-Graham et al., 2008). • An effi cient working environment. DV3D does not attempt to compete with existing analyses pack- • A fl exible, scalable and accessible open-source framework ages in terms of analysis routines but rather acts as a support tool for neuroimaging analysis packages. DV3D allows users to integrate DEALING WITH DIFFERENT DATA TYPES results from a number of different analysis packages, in a variety of Considering the number of different data sources in neuroimaging, formats and in an open-source, platform independent implementa- many different ways to display the results of neuroimaging data tion. DV3D is designed to offer 2D and 3D visualization support have been adopted. for results from a number of neuroimaging acquisition modes and Due to the nature of their individual underlying analysis meth- analysis techniques including magnetic resonance imaging (MRI), ods, many existing software packages are optimized for displaying magnetoencephalography (MEG), positron emission tomography, results in their own preferred way. Figure 1 summarizes some of computed axial tomography and diffuse optical imaging. DV3D has these conventions using FSL, SPM, DTI-Studio15, FreeSurfer, mrV- a highly modular, transparent design and is optimized for integra- ista and EEGLab as examples. Most packages are, understandably, tion of additional display routines and fi le format support. DV3D optimized for the display of imaging results from a limited number provides export routines for high-resolution images, movies and of technologies, protocols, analysis methods and fi le formats. DV3D objects created by the program for data sharing. provides a platform in which the user can display a wider range of FSLView, 3D Slicer and MRICron are three of the most widely data in a number of different formats, be they 2D or 3D. used stand-alone packages for visualizing neuroimaging data, and When considering the data types that a multi-modal neuroim- thus DV3D’s functionality will be most closely compared and con- aging visualization tool may be required to handle, there are at trasted to them. None of these packages (and no other single stand- least four levels of abstraction we need to consider. An example of alone package to the best of our knowledge) offer support for all the complexity of the data structures that require consideration of the multiple analysis outputs of the aforementioned imaging for neuroimaging data processing streams is shown in Figure 2. technologies. DV3D is designed to fi ll this gap. Analyzing and presenting data from MRI protocol subtypes alone DV3D is built on Python, a cross-platform interpreted pro- requires a support for a broad range of data formats. A software gramming language. In DV3D, Python is used to wrap famil- package capable of supporting multi-modal data thus needs to iar, system-native Graphical User Interface (GUI) functionality consider: (a) the technology being used to acquire the different using wxWidgets13 and powerful graphics rendering using the data types, (b) the acquisition settings (or protocol) being used Visualization Toolkit14 (VTK). DV3D’s code base is completely to acquire the data, (c) the analysis techniques used to analyze the platform independent allowing code to run on any system with acquired data, and (d) the format in which the data and results Python, VTK and wxWidgets installed. This minimizes code trans- are stored. lation time and system-dependent error handling, increasing the The fi rst key objective of DV3D is